This invention relates to compositions of nimesulide for topical application.
Nimesulide is a nonsteroidal anti-inflammatory agent (NSAID), which has poor solubility, especially in water. It has been formulated at various concentrations as a suspension in vehicles containing pharmaceutically acceptable excipients. These vehicles typically consist of aqueous gels containing about 1% nimesulide. Nimesulide in suspension may have limited therapeutic activity, as its percutaneous absorption is impaired by the difficulty of releasing free drug molecules from the suspensoid. Solubilised nimesulide, on the other hand, may offer the advantage of immediate availability of free drug molecules to the receptor site, and gels comprising solubilised nimesulide have been prepared using different pharmaceutical solvents. However, when the gel products comprising solubilised nimesulide are applied topically, they produce an unpleasant yellowish stain on the skin and/or clothing.
Many attempts have been made to provide nimesulide compositions of various kinds. They include those described in EP-A-0782855 and EP-A-0812587. In EP-A-0782855 particles of nimesulide are dispersed (not dissolved) in a base component. In EP-A-0812587, nimesulide is incorporated in a medium vaguely described as a xe2x80x9cpercutaneous absorption enhancing vehicle basexe2x80x9d, which comprises water as an essential ingredient and a surfactant such as glyceryl monoolein in an amount of up to 12% w/w.
Accordingly, it is an objective of the present invention to provide nimesulide compositions, which are both therapeutically effective and non-staining or substantially non-staining when applied topically. It has been found that this desirable combination of properties is achieved in the compositions of the present invention. The compositions of the present invention may enable the nimesulide to penetrate the upper layer of the skin (stratum corneum) rapidly. Once within the stat corneum, the nimesulide may be released into the deeper layers of the skin more slowly, which is advantageous in the treatment of the conditions for which nimesulide is used.